U.S. Pat. No. 6,718,193 discloses a method and apparatus for displaying information concerning a tubular structure. The method includes determining a centerline of the tubular structure and a plurality of center points along that centerline, determining a plurality of cross-sections at respective center points, which cross-sections are perpendicular to the centerline, and estimating the values of the diameters associated with each of the cross-sections. The method additionally includes generating a modified image of the tubular structure by displaying a curve that represents the variations of diameter alongside the centerline. According to the method, the centerline of the tubular structure of interest is defined by using automated methods that track this centerline or manually from user input. For each point of the centerline, the cross-section that is normal to the centerline is found, and for each section, information such as the cross-sectional area, the maximum diameter and minimum diameter of the tubular structure in said plane are calculated and stored in memory. The centerline of the tubular structure, which normally shows bends, is aligned to a straight axis. Using this straightened centerline, the tubular structure is also straightened and denoted by “unfolded tubular structure”. Then, along the side of the straighten image of the tubular structure, a set of curves is displayed with the quantitative information of the diameter values previously stored. In particular, the tubular structure may be a vessel. The method of the cited patent includes determining a centerline along at least a portion of the vessel, determining the characteristics of diameters in cross-sections along the centerline and generating an image of a straighten vessel using a straightened centerline. The cited patent further relates to an apparatus for displaying information concerning the vessel. The apparatus includes means for obtaining data concerning an actual vessel, and means for generating a straightened vessel having characteristics of diameters of cross-sections represented by the data. The apparatus further includes means for generating, alongside the image of the straightened vessel, a graphical image showing variation of the parameters of the actual vessel as a function of position along the straighten axis of the straighten vessel image.